ANDERSON, Ind. (WTHR) - The Madison County prosecutor has filed charges in the death of a 4-month-old who died from a heroin overdose last February.

The baby's parents, Tiffany McNutt, 29, and 28-year-old Daniel Jones, are charged with felony neglect of a dependent.

Investigators don't know how Leelan Jones got heroin in his system. What they do know is the infant was living in a "filthy" Alexandria house in conditions so bad, haz-mat crews were called.

"The house these children were in was a disaster. It was condemned. It wasn't habitable for humans," said Madison County Prosecutor Rodney Cummings.

Leelan's 2-year-old brother was also living in the home when the infant died.

Police were called to the home when his mother reported waking to find Leelan not breathing, face down between couch cushions.

An autopsy showed the baby died from a heroin overdose.

"A 4 month old can't even crawl around and pick that up inadvertently," said Cummings.

Multiple tests of McNutt and Leelan's father, Daniel Jones, showed no drugs in their systems. Police tested others who also lived in the house but found nothing there.

"I don't think it's possible this could have happened unless he was given orally. There were no injections on the child's body," Cummings said.

Just as troubling, says Cummings, was how Leelan and his older brother were living. Court documents show investigators found several dogs and cats inside the house, along with feces and urine-soaked items everywhere. Investigators say the kitchen counters were stacked with trash, toys, dishes and old food.

The Department of Children's Services barred Leelan's brother from returning to the home.

"These children who cannot defend themselves or protect themselves have to be protected, and if the adults won't do it, then they'll be held accountable," said Cummings.